The present invention relates to resistor-capacitor (R-C) networks and to the process of manufacturing such networks. More particularly, the invention relates to such networks in which the capacitor is of the kind known as a wound film capacitor.
Wound film capacitors are well known and are routinely manufactured in large quantities. In these capacitors, the plates consist of thin metal films or foils, separated by a plastic film dielectric. The capacitors are referred to as "wound" because the metal-dielectric-metal sandwich is wound into a spiral laminate, thereby providing high values of capacitance in a relatively compact format.
External connecting leads are then attached to the opposite capacitor plates as follows. The metal layers forming the capacitor plates are so positioned that one plate extends all the way out to, or even slightly beyond one end face of the spiral laminate, while the other plate extends to or slightly beyond the opposite end face. Metal, sometimes referred to as "schoopage" metal, is then applied to each end face of the laminate by spraying it on (in molten form), thereby making contact with all the turns of one capacitor plate at one of the end faces and with all the turns of the other capacitor plate at the opposite end face of the spiral laminate. Subsequently, wire connecting leads are welded to these sprayed-on metal contacts.
The resulting assembly is encapsulated, with the connecting wires protruding for connection to other electronic circuit components.
Resistors are, of course, also well known and likewise routinely manufactured in large quantities. In some embodiments, the resistive material is formed into a solid cylindrical body, with wire connecting leads extending from opposite ends of the cylinder. In other embodiments, the resistive material is formed into an elongated path positioned on a separate insulating substrate, connections to other electronic components being made by wire connecting leads attached to opposite ends of the path.
In any case, when such a capacitor and resistor are formed into an R-C network, the total space occupied by the network is, as a minimum, the sum of the space required for each of the components. Indeed, even more space is required to provide room for the connections between resistor and capacitor. Given the powerful trend toward miniaturization of electronic products, this space requirement can readily become burdensome, especially as other electronic components, such as integrated circuits, keep shrinking in size in relation to their functional capabilities.
Accordingly, it is an object of the invention to lessen some of the above-mentioned disadvantages of the prior art.
It is another object to provide an R-C network which requires substantially less physical space than the prior art.
It is another object to provide such a network which occupies a space that is not substantially greater than that of the capacitor alone.
It is another object to provide such a network which requires no additional space for connections between resistor and capacitor.
It is still another object to produce such a network by means of an extremely simple and straightforward process.